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Non-technical summary: There has been a long history of conflicts, studies, and debate over how to both protect rivers and develop them sustainably. With a pause in new developments caused by the global pandemic, anticipated further implementation of the Paris Agreement and high-level global climate and biodiversity meetings in 2021, now is an opportune moment to consider the current trajectory of development and policy options for reconciling dams with freshwater system health. Technical summary: We calculate potential loss of free-flowing rivers (FFRs) if proposed hydropower projects are built globally. Over 260,000 km of rivers, including Amazon, Congo, Irrawaddy, and Salween mainstem rivers, would lose free-flowing status if all dams were built. We propose a set of tested and proven solutions to navigate trade-offs associated with river conservation and dam development. These solution pathways are framed within the mitigation hierarchy and include (1) avoidance through either formal river protection or through exploration of alternative development options; (2) minimization of impacts through strategic or system-scale planning or re-regulation of downstream flows; (3) restoration of rivers through dam removal; and (4) mitigation of dam impacts through biodiversity offsets that include restoration and protection of FFRs. A series of examples illustrate how avoiding or reducing impacts on rivers is possible – particularly when implemented at a system scale – and can be achieved while maintaining or expanding benefits for climate resilience, water, food, and energy security. Social media summary: Policy solutions and development pathways exist to navigate trade-offs to meet climate resilience, water, food, and energy security goals while safeguarding FFRs.
We combined biostratigraphical analyses, archaeological surveys, and Glacial Isostatic Adjustment (GIA) models to provide new insights into the relative sea-level evolution in the northeastern Aegean Sea (eastern Mediterranean). In this area, characterized by a very complex tectonic pattern, we produced a new typology of sea-level index point, based on the foraminiferal associations found in transgressive marine facies. Our results agree with the sea-level history previously produced in this region, therefore confirming the validity of this new type of index point. The expanded dataset presented in this paper further demonstrates a continuous Holocene RSL rise in this portion of the Aegean Sea. Comparing the new RSL record with the available geophysical predictions of sea-level evolution indicates that the crustal subsidence of the Samothraki Plateau and the North Aegean Trough played a major role in controlling millennial-scale sea-level evolution in the area. This major subsidence rate needs to be taken into account in the preparation of local future scenarios of sea-level rise in the coming decades.
Selena Axelrod Winsnes has been engaged, since 1982, in the translation into English, and editing of Danish language sources to West African history, sources published from 1697 to 1822, the period during which Denmark-Norway was an actor in the Transatlantic Slave Trade. Five major books have been published. They describe all aspects of life on the Gold Coast [Ghana], the Middle Passage and the Danish Caribbean islands [US Virgin Islands], as seen by five different men. Each had his own agenda and mind-set, and the books, both singly and combined, hold a wealth of information - of interest both to scholars and lay readers. They provide important insights into the cultural baggage the enslaved Africans carried with them to the America's. One of the books, L.F. Rømer's 'A Reliable Account of the Coast of Guinea' was runner-up for the prestigious International Texts Prize awarded by the U.S. African Studies Association.
Selena Axelrod Winsnes has been engaged, since 1982, in the translation into English, and editing of Danish language sources to West African history, sources published from 1697 to 1822, the period during which Denmark-Norway was an actor in the Transatlantic Slave Trade. Five major books have been published. They describe all aspects of life on the Gold Coast [Ghana], the Middle Passage and the Danish Caribbean islands [US Virgin Islands], as seen by five different men. Each had his own agenda and mind-set, and the books, both singly and combined, hold a wealth of information - of interest both to scholars and lay readers. They provide important insights into the cultural baggage the enslaved Africans carried with them to the America's. One of the books, L.F. Rømer's 'A Reliable Account of the Coast of Guinea' was runner-up for the prestigious International Texts Prize awarded by the U.S. African Studies Association.
This monograph focuses on Gnokholo, a precolonial province of Senegal that has long been landlocked because of its eastern position and inhabited by Mandingoans. The decline of the Malian empire in the 15th century has been confined to a situation of geographical marginality in the foothills of the mountains Of the Fouta Djalon. This book reconstructs the geography, history, economy, culture and social structures of the pre-colonial Gnokholo Kingdom. It fills a deficit insofar as social studies have neglected these populations considered as part of a minority culture. Written in a simple and clear style, this book is in keeping with the tradition of the work of Father Boilat. It is an anthropological collection of a body of knowledge revealing various aspects of the country and the inhabitants of the Gnokholo.
This newly edited volume, Bali Nyonga Today covers about thirty years of (1985-2015) developments in Bali Nyonga, Cameroon. Already well-established as a city-state prior to German colonization in the 19th century, Bali Nyonga continues to adapt to national and global changes since its incorporation into the modern state of Cameroon. With fresh contributions from 12 leading scholars, this volume covers a wide variety of themes and issues including; geographical and historical updates on Chamba migration and settlement in its present homeland in Northwestern Cameroon, an in-depth description of Bali Nyonga cultural associations within the country and the Bali diaspora in the United States, the coexistence of traditional and modern religious worldviews, traditional medicinal practices and life-cycle rituals of significance. Of noteworthy are two chapters devoted to Mungaka, the language of the Balis and its revival in the context of new language policies and developments in African linguistic. Spiced with numerous photos, many of which have never been published, the book is a welcome addition to studies in contemporary African history, culture and society.
The analysis of the global stratospheric meridional circulation, known as the Brewer-Dobson circulation, is an essential part of both experimental and theoretical atmospheric sciences. This large-scale circulation has a crucial influence on the global burden of greenhouse gases and ozone depleting substances throughout the complete atmosphere. This makes it an important factor for the Earth’s radiative budget, which is perceptible at the Earth’s surface despite the remote location of the stratosphere. In the course of climate change it is generally expected that also the Brewer-Dobson circulation undergoes significant changes in structure and strength, although the exact repercussions are still uncertain and thus remain an open scientific question. A general problem for the observational investigation of the dynamical processes in the stratosphere is that residual mean transport cannot be measured directly and hence requires the use of sophisticated proxies. Many studies in the past consider the so-called mean age of air, which is a measure of the average time an air parcel has spent in the stratosphere since passing a certain reference point. While changes in the strength and structure can be detected and visualized using mean age of air, a more thorough distinction between the different involved transport mechanisms of the circulation (residual circulation, mixing) cannot be made. For that, consideration of a full distribution of all relevant transit times through the stratosphere, an age spectrum, is favorable and a powerful tool to analyze the spatial structure as well as possible future changes in detail. Mean age of air and age spectra can be readily derived in atmospheric modeling studies, but an observationally based retrieval is challenging. Mean age of air is usually approximated from measurements of very long-lived trace gas species that act as a dynamical tracer for the stratosphere. The retrieval of age spectra from observations, however, remains an open task for which different methods have been proposed in the past, that often require a combination of strong assumptions and model data explicitly. This is a major issue for a precise and independent investigation of stratospheric dynamics based on measurements. The focus of this cumulative dissertation is on the development process and application of an inversion method to derive stratospheric age spectra from mixing ratios of chemically active substances that combines an applicable and precise ansatz with a minimized amount of necessary model data. Chemically active species have the important benefit that chemistry and transport in the stratosphere are strongly correlated so that the state of depletion of a trace gas can give some information on certain parts of the age spectrum. Considering a sufficient number of distinct trace gases simultaneously, a full approximation of the age spectrum should be possible. The main section of this thesis is split into three parts, which follow the main aspects and key results of the three publications involved (Hauck et al., 2019, 2020; Keber et al., 2020). The newly developed inverse method is based upon the previously established ansatz by Schoeberl et al. (2005), but constrains the shape of the age spectrum by a single parameter inverse Gaussian function. This keeps the balance between applicability and accuracy with a limited amount of measurement data. Additionally, the method introduces a seasonal scaling factor that imposes higher order maxima and minima onto the intrinsically monomodal spectrum based on the seasonal cycle of the tropical upward mass flux to incorporate phases of weaker and stronger transport. A proof of concept of the inverse method is provided using an idealized simulation of the ECHAM/MESSy Atmospheric Chemistry (EMAC) model, where the method is applied to a set of artificial radioactive trace gases with known chemical lifetime. The results imply that the method works properly and retrieves age spectra that match the EMAC reference spectra significantly well on the global and seasonal scale. Only in the lower stratosphere, the performance of the inverse method on the seasonal scale decreases as entrainment into the stratosphere is considered only across the tropical tropopause. Transport across the local extratropical tropopause, however, is a key feature for trace gases in the extratropical lowermost stratosphere so that this entrainment must be included explicitly.
In the second part, the discovered problems are approached to make the inverse method applicable to observations. The formulation of the method is extended to incorporate transport explicitly across the tropical (30° S – 30° N), northern extratropical (30° N – 90° N), and southern extratropical tropopause (30° S – 90° S) each with a single age spectrum that can be inverted independently.
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This article is written from the perspective of phenomenology. Its potential gain for a critical human geography is discussed in contrast to the paradigmatic frame of basic assumptions in constructivism. The example of atmospheres will illustrate another theoretical conception of space. In phenomenological view there happens not only a reality of things but also a circum-actuality is not spatially extended like a house or another material objective. Atmospheres are vital qualities (Dürckheim) we feel like a cloud in our sense perception in situations of awareness. This implies the necessity to make a difference between a material body (Körper) and a felt body (Leib). This epistemic knowledge will improve our critique of neoliberal societies, tuned by aestheticisation especially in glamour CBDs of postmodern cities. Finally there is a close link to the work of Michel Foucault, topped off in his The Hermeneutics of the Subject. References to the Critical Theory (Frankfurter Schule) are connected.